2014 hsc engineering studies

2014 HIGHER SCHOOL CERTIFICATE EXAMINATION

Engineering Studies

General Instructions

• Reading time – 5 minutes

• Working time – 3 hours

• Write using black or blue pen Black pen is preferred

• Draw diagrams using pencil

• Board-approved calculators may be used

• A formulae sheet is provided at the back of this paper

• Write your Centre Number and Student Number at the top of pages 13, 17, 21, 25, 29, 31 and 35

Total marks – 100

Section I Pages 2–11

20 marks

• Attempt Questions 1–20

• Allow about 30 minutes for this section

Section II Pages 13–37

80 marks

• Attempt Questions 21–27

• Allow about 2 hours and 30 minutes for this section

2200

Section I

20 marks Attempt Questions 1–20 Allow about 30 minutes for this section

Use the multiple-choice answer sheet for Questions 1–20.

1 Which of the following is a test performed on a batch of concrete to test its workability?

(A) Compression

(B) Proving

(C) Slump

(D) Tensile

2 The diagram shows couplings experiencing a tensile load.

What type of shear stress is on the pin under the tensile load?

(A) Single

(B) Double

(C) Triple

(D) Quadruple

– 2 –

3 Engineers suspect that there is a flaw in the centre of a large concrete pylon used in a building structure.

Which of the following techniques could be used to find the flaw without damaging the pylon?

(A) Bend test

(B) Radiography

(C) Eddy current inspection

(D) Dye penetrant inspection

4 Which of the following control surfaces on an aircraft is used to control yawing?

(A) Aileron

(B) Elevator

(C) Flap

(D) Rudder

5 Which of the following microstructures shows a water quenched high carbon steel?

(B)(A)

(C) (D)

– 3 –

6 An engineer has designed a warning system to alert ferry masters so that a ferry can only depart when the boarding ramp is on board and the passengers are seated.

The following statements are represented by a 1 if true, or a 0 if false:

A – the boarding ramp is on board

B – the passengers are seated

X – the ferry can depart.

Which row of the table represents the situation where the passengers are not seated even though the boarding ramp is on board?

A B X

(A) 0 1 1

(B) 0 1 0

(C) 1 0 1

(D) 1 0 0

7 The diagram shows an electrical circuit.

3 W

2 W

6 W

12 V

Which of the following correctly calculates the total resistance for this electrical circuit?

(A) ⎛ 1 ⎞ + 2⎜ ⎟1 1

⎜ + ⎟⎝ ⎠3 6

⎛ 1 1⎞ + 2

⎝⎜ ⎠⎟+

3 6

(B)

– 4 –

(C) ⎛ 1 1⎞ 1+ ⎠⎠⎟

+⎝⎜ 3 6 2

(D) ( 3 + 6 ) + 2

8

An insulated conductor has 2000 volts placed across it.

Which instrument should be used to measure the insulation resistance of the conductor?

(A) Ammeter

(B) Megohmmeter

(C) Multimeter

(D) Voltmeter

9 The diagram shows a hydraulic system.

Input piston (Ø15) Output piston (Ø30)

How far will the output piston move if the input piston moves a distance of 20 mm?

(A) 5 mm

(B) 10 mm

(C) 20 mm

(D) 40 mm

– 5 –

10 The diagram shows a bracket folded from a single strip of stainless steel.

R30

R12.5

62

.5

R20.5

If the measurement is taken along the neutral axis, what are the two radii needed to calculate the length of strip required to make the bracket?

(A) 12.5 and 30

(B) 16.5 and 30

(C) 20.5 and 30

(D) 30 and 30

11 Which of the following electrical components does NOT contain a semiconductor?

(A) Diode

(B) Rectifier

(C) Resistor

(D) Transistor

– 6 –

12 The diagram, drawn to scale, shows a handle with a force of 100 N applied.

150 100 N

30°

15

Pin

20

T

Cable

What is the tension T in the cable?

(A) 612 N

(B) 650 N

(C) 687 N

(D) 750 N

13 The diagram shows a pulley system.

120 kg

400 N

NOT TO SCALE

A 400 N effort is needed to lift the 120 kg load.

What is the efficiency of the pulley system?

(A) 300%

(B) 100%

(C) 75%

(D) 33%

– 7 –

14 A pictorial drawing of an inlet valve is shown.

Which of the following sectional front views of the valve complies with AS1100?

(A) (B)

(C) (D)

– 8 –

15 The diagram shows a loaded 12 metre beam and the corresponding shear force diagram.

4 m

A 3 kN

B 3 kN

C D 5 kN

2 m 2 m4 m

2 kN 9 kN

SFD (kN)

2

–1

–4

5

What is the position of the maximum bending moment?

(A) A

(B) B

(C) C

(D) D

16 Ceramics are good insulators because their structure has

(A) covalent and secondary bonds.

(B) ionic bonds with no free electrons.

(C) dipole attraction with the molecules.

(D) metallic bonds with some free electrons.

– 9 –

17 A 2 tonne vehicle is stationary at the top of a 40° slope that is 20 metres long. The vehicle is allowed to roll down the slope.

Ignoring friction, what is the velocity of the vehicle at the bottom of the slope?

(A) 57.7 m/s

(B) 20.0 m/s

(C) 17.5 m/s

(D) 16.0 m/s

18 The diagram shows a bicycle drive mechanism.

Ø700

NOT TO SCALE

70 N

450 N

170 20 teeth

50 teeth

What is the velocity ratio of the mechanism?

(A) 0.16

(B) 0.19

(C) 0.40

(D) 0.48

– 10 –

19 Aluminium copper alloys can be strengthened by a heat treatment process.

Which of the following statements best describes the stages of this process?

(A) Heat to red heat, slowly cool to room temperature.

(B) Heat to about 150°C, quench to room temperature, reheat to slightly above 100°C.

(C) Heat to form a uniform structure, quench to room temperature, reheat to a slightly elevated temperature.

(D) Heat to recrystallisation temperature, cool to room temperature, reheat to slightly below recrystallisation temperature.

20 The diagram shows a 6 metre beam and its cross-section.

8 kN

6 metre beam x x

154 25

0

NOT TO SCALE Enlarged beam cross-section

The beam is loaded at its midpoint. The cross-sectional area of the beam is 110 mm2. The second moment of area I 106 mm4

xx 102 .

What is the maximum compressive stress in the beam?

(A) 11.3 MPa

(B) 18.1 MPa

(C) 22.6 MPa

(D) 29.4 MPa

– 11 –

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– 12 – © 2014 Board of Studies, Teaching and Educational Standards NSW


Engineering Studies Centre Number

Section II

80 marks Attempt Questions 21–27 Allow about 2 hours and 30 minutes for this section

Student Number

Answer the questions in the spaces provided. These spaces provide guidance for the expected length of response.

Question 21 (12 marks)

(a) The photographs show a large single hull ferry and a smaller twin hull ferry.

Single Hull Twin Hull

Contrast how these ferries are used to provide public transport.

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Question 21 continues on page 14

2201 – 13 –

3

Hull

Hydrofoils

Detail of Hydrofoil Geometry

3

Question 21 (continued)

(b) A photograph of hydrofoils in operation on a ferry and the detail of hydrofoil geometry are shown.

Using the information provided, describe how a hydrofoil operates.

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– 14 –


(c)

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(d) Modern wharves, such as the one shown, often use steel structures to support the 3 decking.

Describe a method, other than applying a protective coating, that could be used to protect the steel from corrosion.

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End of Question 21

– 15 –

Outline factors that an engineer needs to consider when designing a ferry wharf. 3

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Engineering Studies Centre Number

Section II (continued)

Student Number


(a) The diagram shows a roof truss supported at each end.

F 30° 30°

A E

C

DB 20 kN

4.33 m

15 m

DRAWN TO SCALE

(i) A force of 20 kN is applied at joint B.

Determine the magnitude and direction of the reaction at the pin joint A.

Force ............ kN Direction .......................


2202 – 17 –

3


(ii) For a different loading, a 30 kN vertical force is applied at joint B and the reaction at the pin joint A is 22.5 kN vertically upwards.

3

F 30° 30°A E

C

D B

30 kN

22.5 kN

15 m

DRAWN TO SCALE

Determine the magnitude and nature of the forces in the members BC and DF.

Force in BC ................ kN Nature .......................

Force in DF ................ kN Nature .......................


– 18 –


(iii) For a different loading, the force in member CF is 29 kN. CF is a solid circular member.

Determine the diameter of member CF if the yield stress for steel is 272 MPa, and a factor of safety of 1.6 is used.

2

Diameter ................................ mm


– 19 –


(b) Flat steel members used for roof trusses could be produced by hot rolling or cold rolling.

(i) Complete the diagrams by naming each process and labelling the grain structure produced.

2

Grain structure Grain structure

............................... grains ............................... grains

............................... rolling ............................... rolling

(ii) Choose one of the processes named in part (i).

Explain how the change in grain structure caused by this process has affected TWO different mechanical properties of the steel.

2

Name of process ....................................................................................

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End of Question 22



Engineering Studies

Section II (continued) Centre Number

Student Number


(a) Outline advantages of polymer roof guttering compared to metal roof guttering. 3

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(b) In the box below, name a polymer that is suitable for roof guttering. Describe the extrusion process for the named polymer. A labelled diagram may be included.

3

Name of polymer ...............................................................................................

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2203 – 21 –


(c) The sketch shows a bent mild steel nail which has become severely corroded after lying in a polymer gutter.

Identify the type of corrosion most likely to have occurred, and on the sketch show the areas of corrosion indicating the anode and cathode regions.

2

Type of corrosion .................................................................................................


– 22 –

4


(d) A transition piece is used to allow water to flow from a gutter to a downpipe. The top view and front view of the transition piece are drawn in third-angle projection.

1, A

B C

D 4

32

2, 1 3, 4

B, A C, D

Complete a half development of the transition piece. The starting position for the seam 1–A is given.

1 •

End of Question 23

– 23 –

BLANK PAGE


Centre Number


Engineering Studies


Student Number


(a) The table shows data obtained by placing an aircraft on three scales, one under each set of wheels.

2

Left-hand main wheels

3 m

12 m

c of m

Scale position

Scale reading

Under nose wheels

550 kg

Right-hand main wheels

Nose wheels Under right-hand main wheels

1400 kg

Under left-hand main wheels

1400 kg

Calculate the distance (d) between the centre of mass (c of m) and the front of the aircraft.

d ........................................ m


2204 – 25 –


(b) Outline how a pitot tube operates in flight.

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2

(c) Describe the function of winglets on modern aircraft.

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– 26 –

2



(d) The diagrams show a turbofan engine and a turbojet engine. 6

Turbofan engine

Turbojet engine

Explain how thrust created by airflow affects the main operations of the two engines. You may add relevant information to the diagrams to support your answer.

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End of Question 24

– 27 –

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Centre Number


Engineering Studies


Student Number


(a) Outline TWO control technologies used to make modern cars safer. 3

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(b) A car with a petrol engine has a 12 volt DC electrical system. 3

How is the electricity generated, stored and then changed to a different voltage system within the car?

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2205 – 29 –

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(c) Outline the advantages of using fibre optics in telecommunications. 3

(d) Explain how a global positioning system (GPS) uses multiple satellites for navigation.

3

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End of Question 25

Centre Number


Engineering Studies


Student Number


(a) The diagram shows a notched bar test. A hammer of mass 11 kg is released from a height of 800 mm. The hammer strikes and fractures the steel specimen at the bottom of the arc, and then continues its swing to a height of 230 mm.

HammerStarting position

230 mm

Final position

Steel specimen

800 mm

(i) Determine the energy lost by the hammer in fracturing the steel specimen. Assume there is no friction loss in the test machine.

Energy lost .................................... J


2206 – 31 –

2


(ii) Complete the table for a type of notched bar impact test. 4

Name of notched bar impact test .........................................................

Sketch how the specimen is held. Indicate on your sketch the position of the notch relative to the striker.

Mechanical property determined .........................................................


– 32 –


(b) A 1.3 tonne boat rests on a trailer inclined at 20° to the horizontal plane. The coefficient of friction between the boat and the trailer is 0.3 and the winch cable is parallel to the trailer boat supports.

20°

winch cable

(i) Calculate the minimum force required in the winch cable to just prevent the boat from slipping back down the trailer.

Force in cable ................................. kN


– 33 –

3


(ii) An electric motor drives a winch to pull the 1.3 tonne boat in part (i) up onto the trailer at a constant velocity of 0.7 m/s. The coefficient of friction between the boat and the trailer is 0.3.

Calculate the power required if the efficiency of the motor is 77%.

3

Power ................................ kW

End of Question 26


Centre Number Section II (continued)

Student Number


Please turn over


Engineering Studies

2207 – 35 –

S


A pictorial drawing of a towbar is shown.

– 36 –

110

50

85

44

25 30°

R40

M 16 × 2

Threaded

holes

Ø22

Ø16

Ø26

Ø50

Ø50

SPHERE

Ø30

BALL MS

SLEEVE MS

TONGUE MS

HEXAGONAL

NUT MS

PRING WASHER

M16 × 2.0 FULL LENGTH THREAD

3840

12

163 75

Ø22

16

40


– 37 –


8 Draw a full sectional view of the fully assembled towbar when viewed from the direction of the arrow. The section plane is to pass through the centre line containing the M16 threaded holes and Ø22 hole in the towbar. Dimension the overall length of the tongue and the diameter of the ball.

End of paper

BLANK PAGE


KE = 1 mv2 ; PE = mgh; W = Fs = ΔPE + ΔKE ; P = ; P = ; =P F2

FP = ; P = P + ρgh

A o

F e σ σ = ; ε = ; E = ; σ = A L ε I

σ σ yield UTSTσ able

= (Ductile); σ = (Brittle)allowa allowableF of S F of S

MA = L

; VR = E ; η = MA

E d VRL

d

AND NAND OR NOR

A B

A B

A B

A B

2E = IR =P I R

Series R = R + R + R + R + � + Rt 1 2 3 4 n

11 1 1 1 1 1Parallel = + + + + � +

R R R R R R t 1 2 3 4 n


Engineering Studies

FORMULAE SHEET

Force, Moments F ma; M Fd = =If a body is in equiilibrium, then ∑F = 0;

x ∑F = 0; ∑M = 0 y

Frictionn F = μN ; μ = tanø

Energy, Work, Power W Fs

vt t

Pressure

Stress and Strt ain My

Machines

Digital Electronics

Electricity, Electronics

2208 – 39 –

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2014 hsc engineering studies

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